标题： 相分离相关氧化物中金属-绝缘体边界的边缘极化子 显示英文标题

标题： Edge polaritons at metal-insulator boundaries in a phase separated correlated oxide

摘要： 具有相关性的过渡金属氧化物，例如铜氧化物、镍氧化物和锰氧化物，通常被认为是“劣质金属”，其中高的电磁损耗抑制了在贵金属、二维电子气体和石墨烯中观察到的常规等离子体效应。 然而，利用中红外近场光学纳米显微镜，我们证明了在钕镍氧化物（NdNiO$_{3}$）薄膜中导电区域与绝缘区域之间的边界处，混合声子-等离激元性质的强约束且长程传播的边缘极化子（EPs）的出现，这种现象通过近场信号相位的显著峰值来表征。 我们的模拟结果显示，EPs的电磁特性很大程度上依赖于边缘的光滑度，在突然的边缘处是由一维光学边缘态（ES）引起的，而在宽边界的情况下则由介电常数接近零（ENZ）的吸收所控制。 我们的发现突显了非局域等离激元效应在相分离的相关氧化物近场成像中的关键作用，并为这类材料中的红外等离激元学开辟了新的途径。 显示英文摘要

摘要： Correlated transition metal oxides, such as cuprates, nickelates, and manganites, are typically considered "bad metals", where high electromagnetic losses suppress the conventional plasmonic effects observed in noble metals, 2D electron gases, and graphene. Nevertheless, using mid-infrared near-field optical nanoscopy, we demonstrate the emergence of strongly confined and long-propagating edge polaritons (EPs) of mixed phonon-plasmon nature at the boundaries between conducting and insulating regions in thin NdNiO$_{3}$ films, fingerprinted as a pronounced peak of the near-field signal phase. Our simulations reveal that the electromagnetic nature of the EPs depends significantly on the edge smoothness, being caused by a one-dimensional optical edge state (ES) at abrupt edges while being governed by the epsilon-near-zero (ENZ) absorption in the case of broad boundaries. Our findings highlight the critical role of nonlocal plasmonic effects in near-field imaging of phase-separated correlated oxides and open new avenues for infrared plasmonics in this family of materials.